基于力约束的空心涡轮叶片陶芯定位方法

精铸蜡型作为空心涡轮叶片精铸过程重要的前期工艺转接件,其壁厚精度主要由蜡型模具型腔与内部陶芯的位置匹配关系决定。由于陶芯在模具内完全依靠定位元件实现空间定位,为减小由定位误差引起的陶芯位姿漂移,提出了一种基于力平衡约束的空心涡轮叶片精铸模具陶芯定位布局优化方法。首先,通过建立陶芯定位误差传递模型,揭示了定位误差与陶芯空间位姿扰动量之间的映射关系;其次,根据力平衡原理构建了基于力约束的陶芯定位布局优化模型;之后,针对陶芯表面定位候选点的离散分布特性,结合遗传算法给出了陶芯定位布局点的详细求解策略。最后,仿真对比证明了利用本文所提方法获得的陶芯定位方案可以在保证陶芯定位稳定性的同时提高陶芯定位精度,此外,按照优化后的定位方案压制实际蜡型,壁厚检测结果也进一步表明所提方法的有效性。

Force-constraint method for localization of ceramic core of hollow turbine blade

The wax pattern is always used as a dimension transfer component in near-net-shape casting process for a hollow turbine blade,and its wall-thickness accuracy entirely depends on the positional relationship between the die cavity of the wax pattern and the internal ceramic core.Generally,the ceramic core is located in the wax pattern die through a series of locating rods.In order to reduce the positional shift of the ceramic core caused by locating errors,a locating layout optimization method based on the force-balance constraint is proposed in this paper.An error transfer model,which formulates the mapping relationship between localization errors and perpetuation of the ceramic core,is established.According to the static equilibrium theory,an optimization model for locating the layout of the ceramic core is then proposed based on gravity constraint.Considering the discrete feature of locating the candidate point on the surface of the ceramic core,a solving strategy for the optimization model is given by utilizing the genetic algorithm.Comparisons of simulation results prove that the locating layout optimized with the method in this paper can improve the localization accuracy of the ceramic core,while guaranteeing the localization stability.Based on a wax injection experiment,the feasibility of the optimization result is also demonstrated.